The invention relates to a telescopic adjustable support in the form of an arm or rail.
Telescopic adjustable supports in the form of arms or rails are known, with numerous designs for a wide variety of applications. Swiss Patent 663,881 for example teaches the provision of office equipment such as keyboards and the like with such supports to permit changing their positions. This known telescopic extendable horizontal support is constructed to be as easy as possible to pull out and push in. When the device supported by the support is actuated or when certain actions need to be performed on an object supported by the support, forces act on the device and/or object which can lead to a pushing-in or pulling-out movement of the telescopic arm that is undesirable at this point in time. A locking screw is provided to prevent such undesirable changes in the length of the support. To pull the support out or to push it in, the locking screw must be loosened and retightened after the length adjustment has been made. This makes operation of the support inconvenient. German Utility Model 87 09 871 teaches a height-adjustable horizontal support for data processing equipment. The support has a telescopic section bent at an angle and engaging a guiding telescopic section inclined to the vertical. The weight acting on the support tilts the two telescopic sections with respect to one another, looking them automatically into any extended position. Lifting the support releases the lock and allows the height to be adjusted telescopically. No provision is made for adjusting the length of the support horizontally. In addition, the automatic lock known from German Utility Model 87 09 871 can be used only for relatively short telescopic sections, which are subjected to considerable mutual tilting caused by the tilting movement involved. In the case of a long horizontally extendable telescopic arm, as shown in Swiss Patent 663,881 for example, pushing the arm further inward produces only a minimal mutual tilting of the axes of the two interlocking telescopic parts, so that no automatic locking action occurs.
The goal of the invention is to provide a telescopic adjustable support in the form of an arm or track which automatically locks into any desired position when extended and, to avoid undesirable telescopic movement without additional manual actuation being required to lock and release the lock.